This invention relates to methods and apparatus for transporting articles from a magazine. In particular, this invention relates to methods and apparatus that use a rotary mechanism that employs an offset shaft to unload articles from a magazine.
In typical assembly line operations, articles must be removed from a magazine and transported to an assembly line in a continuous fashion. Rotary unloaders are commonly used to unpack articles from a magazine. The transport of the articles should be accomplished in a manner to place the articles in a position convenient for further processing. For example, articles such as corrugated trays may be removed from a magazine and placed onto the assembly line in a position suitable for packaging products. In other preferred aspects, lids may be placed on boxes or labels may be applied to packages. Because of the high-speed operation of assembly lines, these unpacking devices must provide reliable, high-speed transport. Rotary devices are often used to provide high speed transport.
However, rotary devices, when removing an article from a magazine, are subject to the problem of roll back into a following article because of the rotational movement. Also, placement of the article on a receiver is more violent when using rotational movement. Thus, it is generally desirable for the rotary unloader to remove articles from the magazine using a substantially linear motion. It is also often desirable for the rotary unloader to place the article using a generally linear motion. The linear motion facilitates removal of the article from the magazine without undue damage to the article.
Some rotary unloaders employ multiple axes of rotation and reciprocating motion in order to achieve a generally linear motion when removing articles from a magazine. With these rotary unloaders, care must be taken to ensure that the article is not disturbed by the mechanism of the rotary unloader. Thus, it is desirable that the rotary mechanism maintains an outward disposition of the article being transported. This disposition may be accomplished using additional axes of rotation and selection of gear ratios. For example, U.S. Pat. No. 4,643,633 to Lashyro employs a system using three axes of rotation to maintain an outward disposition of an article as it is transferred from a pick position to a place position. However, employing multiple axes of rotation complicate the design and function of a rotary device. With rotary unloaders that do not maintain an outward disposition of transported articles, such as disclosed in U.S. Pat. No. 5,019,207 to McCoy, the rotary unloader structure must allow for clearance for movement through an inwardly disposed position. This further limits the size of the article that may be transported. Moving the article through an inwardly disposed position also increases the amount of travel the article must move through between the pick location and the place location.
Rotary unloaders may operate more efficiently and quickly by employing multiple handlers to transport items. Rotary unloaders have employed multiple handlers where distinct gear systems are used to drive each handler in order to provide a reciprocating action during the picking and placing motions. While improving efficiency, each additional distinctly driven handler multiplies the complexity of the mechanism of the rotary unloader.
These shortcomings are inherent in the design of current rotary unloaders. There is therefore a need for methods and apparatus using a rotary unloader that do not suffer from the deficiencies of existing apparatus. In particular, there is a need for methods and apparatus that allow for quick and efficient unloading that maintain an outward disposition of a transported article without multiplying the complexity of the unloader. These methods and apparatus should provide a reciprocating action during picking and placing motions while minimizing the travel of the article. There further exists a need for methods and apparatus that allow for multiple handlers driven by a single gear system. There is also a need for methods and apparatus using a rotary unloader for transporting articles from a magazine that minimize the possibility of mishandling the article and of interrupting the assembly line process because of rotational movement. Furthermore, rotary unloaders that employ a continuous motion may operate at higher speeds than unloaders that must interrupt rotational motion to achieve a linear motion for unloading. In addition, methods and apparatus employing a continuous motion may be more reliable and employ fewer moving parts in order to accomplish the unloading.